Hydraulic stabilizer for use with a downhole casing cutter

Abstract

A downhole stabilizer includes a radial expansion assembly deployed about, and configured to rotate substantially freely with respect to, a tool mandrel. The expansion assembly preferably includes at least one stabilizer block configured to extend radially outward from the mandrel into contact with a wellbore casing string. When deployed between uphole and downhole cones, the stabilizer block preferably includes a plurality of angled splines configured to engage corresponding splines disposed on the cones. Relative axial motion between the stabilizer block and the cones causes a corresponding radial extension or retraction of the block.

We claim: 
     
       1. A downhole stabilizer comprising:
 a tool body arranged and designed to couple with a downhole tool string, the tool body including an axial through bore and a mandrel; 
 a first cone deployed about the mandrel, the first cone including a first cone recess, the first cone recess having a set of first cone splines disposed in at least one axial wall thereof; 
 a second cone deployed about the mandrel, the second cone including a second cone recess, the second cone recess having, a set of second cone splines disposed in at least one axial wall thereof; and 
 a stabilizer block deployed axially between the first and second cones and carried in the first and second cone recesses, the stabilizer block having at least two sets of stabilizer block splines disposed on a lateral face thereof, a first of the sets of stabilizer block splines arranged and designed to complement and engage the set of first cone splines and a second of the sets of stabilizer block splines arranged and designed to complement and engage the set of second cone splines; 
 wherein the first cone, the second cone, and the stabilizer block are configured to rotate substantially freely with respect to the tool body, and wherein the sets of first cone splines, second cone splines, and stabilizer block splines are each angled with respect to a longitudinal axis of the tool body such that axial translation of the second cone with respect to the first cone either radially extends or retracts the stabilizer block. 
 
     
     
       2. The downhole stabilizer of  claim 1 , wherein the second cone is configured to translate axially with respect to the first cone in response to a differential pressure between the through bore and a region external to the tool body. 
     
     
       3. The downhole stabilizer of  claim 1 , wherein the first cone, the second cone, and the stabilizer block are configured to rotate substantially freely with respect to at least the mandrel of the tool body. 
     
     
       4. The downhole stabilizer of  claim 1 , comprising three stabilizer blocks deployed at angular intervals of about 120 degrees about a circumference of the mandrel. 
     
     
       5. The downhole stabilizer of  claim 1 , further comprising a piston deployed about the mandrel and axially between the second cone and a shoulder deployed on the tool body. the piston being rotationally fixed to the tool body and configured to reciprocate axially with respect to the tool body. 
     
     
       6. The downhole stabilizer of  claim 5 , wherein the piston comprises an internal surface in fluid communication with the through bore such that a differential pressure in the through bore urges the piston and the second cone axially towards the first cone, thereby urging the stabilizer block radially outward. 
     
     
       7. The downhole stabilizer of  claim 6 , wherein the second cone and the piston are spring, biased away from the first cone and towards the shoulder, thereby spring biasing the stabilizer block radially inward. 
     
     
       8. The downhole stabilizer of  claim 1 , wherein the first cone is axially fixed to the mandrel. 
     
     
       9. The downhole stabilizer of  claim 1 , wherein an angle between the first set of stabilizer block splines and the longitudinal axis is in the range from about 10 to about 30 degrees. 
     
     
       10. The downhole stabilizer of  claim 1 , wherein an angle between the second set of stabilizer block splines and the longitudinal axis is in the range from about 60 to about 80 degrees. 
     
     
       11. The downhole stabilizer of  claim 1 , wherein the first and second sets of stabilizer block splines are substantially orthogonal to one another. 
     
     
       12. A string of downhole tools configured to cut a wellbore casing, the string of downhole tools comprising:
 a casing cutting tool; and 
 at least one downhole radial stabilizer including:
 a tool body coupled with the casing cutting tool, the tool body including an axial through bore and a mandrel; 
 a first cone deployed about the mandrel, the first cone including a first cone recess, the first cone recess having a set of first cone splines disposed in at least one axial wall thereof; 
 a second cone deployed about the mandrel, the second cone including a second cone recess, the second cone recess having a set of second cone splines disposed in at least one axial wall thereof; and 
 a stabilizer block deployed axially between the first and second cones and carried in the first and second cone recesses, the stabilizer block having at least two sets of stabilizer block splines disposed on a lateral side thereof, a first of the sets of stabilizer block splines configured to complement and engage the set of first cone splines and a second of the sets of stabilizer block splines configured to complement and engage the set of second cone splines; 
 wherein the first cone, the second cone, and the stabilizer block are configured to rotate substantially freely with respect to the tool body, and wherein the sets of first cone splines, second cone splines, and stabilizer block splines are each angled with respect to a longitudinal axis of the tool body such that axial translation of the second cone with respect to the first cone either radially extends or retracts the stabilizer block. 
 
 
     
     
       13. The string of downhole tools of  claim 12 , wherein the first cone, the second cone, and the stabilizer block are configured to rotate substantially freely with respect to at least the mandrel of the tool body. 
     
     
       14. The string of downhole tools of  claim 12 , wherein:
 an angle between the first set of stabilizer block splines and the longitudinal axis is in the range from about 10 to about 30 degrees; and 
 an angle between the second set of stabilizer block splines and the longitudinal axis is in the range from about 60 to about 80 degrees. 
 
     
     
       15. The string of downhole tools of  claim 14 , wherein the first and second sets of stabilizer block splines are substantially orthogonal to one another. 
     
     
       16. The string of downhole tools of  claim 12 , wherein:
 the casing cutting tool is configured such that the string of downhole tools translates axially as cutting progresses during a casing cutting operation; and 
 the downhole radial stabilizer is configured to provide radial stabilization while allowing the string of downhole tools to translate axially. 
 
     
     
       17. The string of downhole tools of  claim 12 , wherein the casing cutting tool comprises at least one radially extendable cutting ann. 
     
     
       18. The string of downhole tools of  claim 17 , wherein the radially extendable cutting arm is configured to pivot radially outward about a hinge point. 
     
     
       19. The string of downhole tools of  claim 12 , wherein both the downhole radial stabilizer and the casing cutting tool are hydraulically actuated. 
     
     
       20. The string of downhole tools of  claim 12 , comprising first and second of the downhole radial stabilizers, the casing cutting tool being deployed axially between the first and second of the downhole radial stabilizers. 
     
     
       21. A method for forming a circumferential cut in a wellbore casing string, the method comprising:
 (a) rotating a downhole tool string at a predetermined location in a cased wellbore, the tool string including at least one radial stabilizer and a wing-type casing cutter; 
 (b) causing at least one stabilizer block to extend radially outward from the radial stabilizer into contact with the cased wellbore, the extension of the stabilizer block operative to radially stabilize the tool string in the wellbore while allowing for axial translation of the tool string in the wellbore and for rotation of the at least one stabilizer block substantially freely with respect to a tool body of the at least one radial stabilizer; 
 (c) causing at least one cutting arm to extend radially outward from the wing-type casing cutter into contact with the cased wellbore, the extension Of the cutting arm operative to begin cutting the wellbore casing string; and 
 (d) forming a circumferential cut in the wellbore casing string via continued rotation of the tool string and extension of the cutting arm thereby causing, the tool string to translate axially in the wellbore. 
 
     
     
       22. The method of  claim 21 , wherein the at least one stabilizer block and the at least one cutting arm are hydraulically actuated and extended substantially simultaneously in (b) and (c).